在氨基甲酸乙酯麻醉的大鼠中，CA1锥体神经元基底和顶端树突的长时程增强的差异。

Difference in LTP at basal and apical dendrites of CA1 pyramidal neurons in urethane-anesthetized rats.

作者信息

Roth L R, Leung L S

机构信息

Department of Physiology and Clinical Neurological Sciences, University of Western Ontario, London, Canada.

出版信息

Brain Res. 1995 Oct 2;694(1-2):40-8. doi: 10.1016/0006-8993(95)00767-k.

DOI:10.1016/0006-8993(95)00767-k

PMID:8974662

Abstract

In urethane-anesthetized rats, excitatory currents in hippocampal CA1 area following local stimulation were analyzed using the current source density technique. Systematic variation of stimulus depth revealed two dominant patterns of activation: basal versus apical dendritic excitation. The basal dendritic excitation (sink) was maximal after stimulation of stratum oriens; its onset latency was consistent with a monosynaptic excitation, and a late (presumed di- and polysynaptic) sink at the apical dendrites was observed. The apical dendritic excitation (sink) was maximal after stimulation of stratum radiatum; the early latency, presumed monosynaptic excitation was followed by a late, weak basal dendritic sink. Theta-frequency primed bursts of either high (400 microA) or low intensity (40-70 microA; 2 x threshold intensity) was delivered to either stratum oriens or radiatum, and long-term potentiation (LTP) was assessed. LTP was observed in both positive and negative components of the dipole field, as well as the (active) sink and (passive) source. Tetanus of stratum oriens resulted in a significant (P < 0.05) potentiation of the monosynaptic basal sink (at 2 ms from onset) following either high (135 + 11%, means +/- S.E.M., n = 7) or low intensity tetanus (178 +/- 21%, n = 7). Tetanus of stratum radiatum resulted in significant potentiation of the rise of the apical sink only for a high (173 +/- 51%, n = 6), but not for a low intensity tetanus (106 +/- 28%, n = 6). Significant LTP of the late apical sink was found following a high intensity tetanus of stratum oriens (155 +/- 15%, n = 7), but no significant change of the late basal sink was found following tetanization of stratum radiatum (118 +/- 20%, n = 6). UP of either the apical and basal sinks was blocked by intraventricular infusion of +/- 2-amino-5-phosphonovalerate, an N-methyl-D-aspartate antagonist. Thus, UP has a lower threshold at the basal than apical synapses of CA1 cells.

摘要

在氨基甲酸乙酯麻醉的大鼠中，使用电流源密度技术分析了局部刺激后海马CA1区的兴奋性电流。刺激深度的系统变化揭示了两种主要的激活模式：基底树突兴奋与顶树突兴奋。刺激海马下托后，基底树突兴奋（电流汇）达到最大；其起始潜伏期与单突触兴奋一致，并且在顶树突观察到一个晚期（推测为双突触和多突触）电流汇。刺激辐射层后，顶树突兴奋（电流汇）达到最大；早期潜伏期，推测为单突触兴奋之后是晚期、微弱的基底树突电流源。将高频（400微安）或低频（40 - 70微安；2倍阈强度）的θ频率引发脉冲施加到海马下托或辐射层，并评估长时程增强（LTP）。在偶极场的正向和负向成分以及（活跃的）电流汇和（被动的）电流源中均观察到LTP。海马下托的强直刺激导致高频（135 + 11%，平均值±标准误，n = 7）或低频强直刺激（178 ± 21%，n = 7）后单突触基底电流汇（起始后2毫秒时）的显著（P < 0.05）增强。辐射层的强直刺激仅在高频（173 ± 51%，n = 6）时导致顶电流汇上升的显著增强，而低频强直刺激（106 ± 28%，n = 6）时则未出现。在海马下托高频强直刺激后发现顶树突晚期电流汇有显著的LTP（155 ± 15%，n = 7），但辐射层强直刺激后基底树突晚期电流汇未发现显著变化（118 ± 20%，n = 6）。脑室注射N - 甲基 - D - 天冬氨酸拮抗剂±2 - 氨基 - 5 - 磷酸戊酸可阻断顶树突和基底树突电流汇的LTP。因此，CA1细胞的基底突触处LTP的阈值低于顶树突突触处。